Electron discharge device control system



June 8, 1937.

I. K. DORTORT ELECTRON DISCHARGE DEVICE CONTROL SYSTEM 5 Sheets-Shed 1 Filed Feb. 5, 1934 J 8, 1937. l. K. DCRTORT 2,083,149

ELECTRON DISCHARGE DEVICE CONTROL SYSTEM Filed Feb. 5, 1954 s Shets-Sheet 2 WY cane/ June 8, 1937. am-om- 2,083,149

ELECTRON DISCHARGE DEVICE CONTROL SYSTEM Filed Feb. 5, 1934 3 sheets sheet 5 u f /t a, f a/ P [/7' i ,a dig. 4

EM /X04,

Mme/may Patented June 8, 1937 ELECTRON DISCHARGE DEVICE CONTROL SYSTEM Isadore K. Dortort, Milwaukee, Wis., aasignor to Allis-Chalmers Manufacturing Company, Milwaukee. Wis, a corporation of Delaware Application February 5, 1934, Serial No. 109,821

12 Claims. (or. 175-363) This invention relates in general to improvements in electron discharge device control systems and more particularly to means for impressing, on the control electrodes of an electric valve, potential impulses of short duration to control the flow of current therethrough in an accurate and emcient manner.

Electric valves are frequently utilized for controlling the flow of current through circuits associated therewith to thereby constitute systems such as alternating current rectifying, direct cun'ent inverting, frequency changing and other systems. In such valves the flow of current is generally released periodically througheach anode by the action of suitable means such as control electrodes, the flow of current being prevented by maintaining the control electrode below the so-called critical potential, which is approximately cathode potential, and being released by bringing the control electrode to a potential above the critical potential. In valves of the vapor type the critical potential depends on the operating conditions within the valve so that when the control electrode potential varies gradually, the flow of current through the anodes is released at intervals which are not accurately defined. It is, therefore, desirable to impress, on the control electrodes, a control potential suddenly pasing from a material negative value to a material positive value. In addition, in

direct current inverting systems the control electrodes must receive potential impulses of short duration because each control electrode must prevent reestablishment of the flow of current' through the associated anode immediately after the end of the working period thereof and must, therefore, be returned to a negative potential before such instant. Control potentials having positive impulses of short duration may be conveniently obtained by means of circuits supplied provide a control system for an electron dis charge device in which the control electrodes of the device receive positive impulses of short duration.

Another object of the present invention is to 6 provide a control system for an electron discharge device in which the control electrodes of the device receive potentials from circuits containing oscillative impedance devices.

Objects and advantages other than those above 10 described will be apparent from the following description when read in connection with the accompanying drawings, in which:

Fig. 1 diagrammatically illustrates one embodiment of the present invention applied to the 15 control of an electric valve operable either as an Fig. 3 diagrammatically illustrates a portion- 5 of a. modified embodiment of the present invention in which the control electrodes of the valve .receive' voltages taken through a. transformer from a reactor constituting part of an oscillative circuit;

Fig. 4 is a diagram illustrating the wave form of some of the voltages appearing in the circuits of the embodiment illustrated in Fig 3.

Referring more particularly to the drawings by characters of reference. reference numeral 6 35 designates an alternating current line operating at any suitable voltage of any desired frequency and herein represented as a three phase line. The system to be hereafter described is designed to perform rectification of current obtained from line 6 and the supply thereof to a direct current line I, 8 and also inversion of current obtained from line I, 8 and the supply thereof to line 6. Line 6 is accordingly connected with the primary winding of a. transformer 9 having a secondary winding ll comprising a. plurality of phase displaced portions. The diiferent portions of winding ll may be connected to form a. neutral point connected with conductor 1 in any manner known in the. art. and are severally connected with the anodes I! of an electron discharge device such as an electric valve ll of the vapor type having a cathode l4 connected with conductor 8. Valve I3 is provided with a. plurality of control electrodes 15 severally associated a with the anodes and receiving control potentials from circuits to be described immediately hereafter. The potential of cathode M will be taken as datum for the control potentials impressed on the control electrodes of the valve and, similarly, the control potentials impressed on the control electrodes of any auxiliary valves will be referred to the potentials of the associated cathodes.

10 Each control electrode I5 is generally energized at a negative potential through a battery It connected therewith through resistors l2 and I9 and connected with conductor 2. The positive terminal of battery It is connected with each of the 16 anodes of a plurality of auxiliary valves as at anode 20 of a valve 2| having a control electrode 24 and a cathode 2B, the circuit of each valve being completed by connecting the cathode thereof as at 25 with the negative terminal of the bat- 20 tery l6 through a reactor as at 22 and a capacitor as at 22. The auxiliary valves may be of any suitable type, but the operation of the system illustrated in the present embodiments will be described under the assumption that the auxiliary 25 valves are of the discontinuously controllable vapor type. Each control electrode as at 24 is energized in relation with the voltage cycle of line 8 and of winding II by means of a transformer 28 energized from line B which may have 30 the windings thereof in variable inductive relation to vary the phase relation between the primary and secondary voltages thereof. The secondary winding ll of transformer 22 is preferably composed of a plurality of phase displaced portions connected to form a neutral point connected with the negative terminal of battery It through a bias battery 21, the different portions of the winding being severally connected with the control electrodes of the auxiliary valves.

40 The operation of the system will be described assuming that current received from line 6 is to be rectified and supplied to line I, 2, but it will be understood that a converse functioning is obtained by a similar sequence of operations.

45 Fig. 2 shows curves representing the voltages of the several anodes of a rectifier |2 drawn with respect to the potential of conductor I, curve 28,

for example, representing the voltage impressed on anode l2 by the associated portion of winding Line 22 represents the potential of cathode l4 and is therefore the reference line for the control potentials impressed on the control electrodes such as control electrode I. The potential of the negative terminal of battery It is then 56 represented by line 2| and the potential of the neutral point of winding I1 is represented by line 22. Curve 22 then represents the potential of control electrode 24. the alternating component of such potential being adjusted in suitable phase relation with the potential of anode |2 by adjustment of transformer 22.

At the time immediately prior to the time represented by point A. cathode 25 is at the negative potential of battery It represented by line 2|. 06 control electrode 24 is then negative with respect thereto and valve 2| is therefore non-conductive. Control electrode II is accordingly maintained at negative potential represented by line 2|. At time A control electrode 24 becomes positive and 70 releases the flow of current through valve 2|. The voltage drop in the discharge within valve 2| being neglected for the purpose of simplifying the present explanation, cathode 22 which was previmisly at the potential represented by curve II is suddenly brought to substantially the potential represented by line 29. The potential of the junction point of reactor 22, control electrode I5 and capacitor 22 cannot, however, suddenly change but will change gradually in response to the gradual charge of capacitor 22 which is retarded by the action of reactor 22 and of resistor l9. Such potential therefore follows a substantially sinusoidal curve BC, reaching the potential of cathode l4 at point C. At such time the flow of current through reactor 22 has become maximum and the magnetic energy stored within reactor 22 begins to be dissipated for continuing charging capacitor 22 at an ultimate potential somewhat less than twice the voltage of battery Hi.

The potentials of the junction point and control electrode I5 accordingly followcurve portion CE, which is somewhat less in amplitude than curve portion BC. At point E the flow of current charging capacitor 22 through valve 2| is no longer maintained by reactor 22 and such flow of current tends to reverse. As a result of the valve action of valve 2| a reversal of the flow of current is however not possible and all flow of current through valve 2| therefore ceases. The potential difference across the terminals of reactor 22, which was caused by the flow of current therethrough, totally collapses and capacitor 22 discharges through resistor I! at a rate depending upon the relative values of the capacity and of the resistance thereof respectively, The potential of control electrode l5 accordingly follows curve portion EHF reaching "line 3| when the discharge of capacitor 22 is complete.

At time C, at which control electrode 5 becomes positive, the flow of current through anode I2 is released and occurs at a voltage following a portion of the curve 28. At time A cathode 25 is suddenly brought from the negative potential represented by line 2| to the potential of cathode l4 and remains at substantially such potential during the conductive period of valve 2| ending at point D. At such point current ceases to flow through valve 2| and, as a result of the collapse of the voltage across reactor 22, cathode 25 is suddenly brought to the positive voltage of the junction point represented by point E and thereafter follows the same curve at the junction point. It therefore appears that the potential of cathode 2!! follows a composite curve BADEHFG, the oathode becoming suddenly positive with respect to control electrode 24 immediately after such control electrode had momentarily become positive with respect to the cathode for releasing the flow of current therethrough. The flow of current through valve 2| will therefore be reestablished only after an interval of one cycle following time A provided that during the cycle the potential of control electrode 24 represented by curve 22 remains negative with respect to curve BADEHFG as shown in Fig. 2.

During each cycle of the voltage of line I, control electrode II therefore receives a single positive impulse of short duration represented by curve CEH which may be made to occur during any desired time interval by suitable choice of the reactor 22, capacitor 22, resistor l2 and battery l8. Similar potentials are impressed on the remaining control electrodes of valve |2 to cause the flow of current through the several anodes of the valve to occur in sequence to supply current to line I, I at a voltage represented by curve 22. The average output voltage of valve |2 may be varied by varying the time of the cycle at which each anode becomes conductive,such

result being obtained by varying the time of the cycle at which each auxiliary valve becomes conductive. The time A at which each valve such as 2| becomes conductive being determined by the intersection of curve 33 with line 3|, it will be seen that such time may be varied by either adjusting transformer 28 to change the phase relation between the primary and secondary voltage thereof or by changing the amount of battery 21 inserted in the circuit thereof.

In the embodiment partly illustrated in Fig. 3 the cathodes of the auxiliary valves are directly connected with the negative terminal ,of battery l6 and the anodes of the auxiliary valves are connected with the positive terminal of the battery through a reactor as at 22 and a capacitor as at 24. The resistors as at l9 are omitted and control potentials are impressed on the control electrodes through a plurality of transformers such as 31 each having a primary winding connected across a reactor 22 and having a secondary winding connected between the negative terminal of battery l6 and the control electrode. A resistor as at 38 is connected across each' capacitor to dissipate the charge thereof during each cycle of the voltage of line 8. If so desired the transformers as at 3'I may be replaced by secondary windings provided on the cores of each of the reactors without thereby affecting the operation of the system.

In Fig. 4, the voltages appearing in the circuit of valve 2| have been shown with separate reference lines in order to clarify the drawings, line 29 representing the potential of cathode H in each portion of the figure and line 3| representing the potential of the negative terminal of battery I! in each portion. The potential of anode I2 is again represented by curve 23 with reference to the potential of conductor I. The potential of control electrode 24 is again represented by the curve 83 becoming positive with respect to line 3| at a time represented by point K, at which time control electrode 24 releases the flow of current through valve 2|. At a time immediately prior to time K, anode 20, both terminals of capacitor 23, and the entire reactor 22 were at the potential represented by line 23. At time K anode 20 is suddenly brought to substantially the potential of the negative terminal of battery l6, represented by line 3|. The potential of the junction point of reactor 22 and capacitor 23 is represented by curve 33 following line 23 to point K and suddenly reaching line 3| at point P, for the reason that at time K, capacitor 23 is entirely discharged and the potentials of both terminals thereof therefore momentarily vary in identical manners. The flow of current being established through valve 2|, capacitor 23 gradually charges at a potential ultimately somewhat less thantwice the voltage of battery I8. the junction point therefore following a sinusoidal curve PL. Capacitor 23 being at its maximum charge, the flow of current through valve 2| tends to reverse and is prevented from reversing as a result of the valve action of valve 2|. The potential difference across reactor 22 accordingly collapses and the junction point is suddenly brought to the potential of cathode H at point M and remains at such potential during the remainder of the cycle. The primary winding of transformer 31 receives a voltage which is equal to the voltage difference between the junction point and cathode l4 and is therefore represented by curve 39. The secondary winding of transformer 31 accordingly impresses on control electrode IS a potential, represented by curve 42, such curve having a wave shape similar to the wave shape of curve 39 but being reversed as a result of the connections of transformer 31 and being displaced with respect to its axis 3| because the average voltage over a complete cycle must be zero. Such voltage being impressed in series with the voltage of battery It, the potential of control electrode I5 represented by curve 42 must be referred to line 29 and is therefore generally negative and presents positive impulses of short duration and steep wave front once per cycle of the voltage of line 6.

In the present embodiment, cathode25 is constantly maintained at the negative potential of battery l6 represented by line 3|. At time K anode 20 reaches substantially such potential at point P and is maintained at such potential to point Q, being then suddenly given a negative potential impulse bringing it to point R as a result of the collapse of the voltage in reactor 22. The charge of capacitor 23 then gradually dissipates to vary the potential of anode 20 in accordance with curve RTS. Such curve intersects curve 3| at point T showing that anode 20 becomes positive with respect to cathode 25 at such point. As valve 2| must remain non-conductive for the remaining portion of the cycle, it is therefore necessary that control electrode 24 again becomes negative at a time represented by point U prior to point T as shown in the figure. The above sequence of operations is repeated for each control electrodeand each anode of valve l3 to release the flow of current therethrough at a voltage represented by curve 36. Such voltage may be adjusted as in the previous embodiment gized from a system for generating a periodic potential. Each system comprises a circuit including battery It and a reactor 22 with a capacitor 23 constituting an oscillative impedance element, a resistor ill or 33 for discharging the capacitor and a valve 2| controlling the flow of cur rent through the circuit. Each valve 2| is provided with discharge controlling means such as control electrode 24 connected for cyclically controlling the flow of current through the circuit of the valve and which is energized in relation with the voltage cycle of winding II by means of transformer 28 at potentials of signs and magniiudes operative to cause valve 2| to be alternately conductive and non-conductive at recurring intervals in relation with the voltage of transformer 26. Such action is regulated by adjustment of transformer 28 or of battery 21. The connections of the circuits are such as to impress, on a load circuit connecting control electrode I! to cathode M, a potential component similar to a component of a potential across a portion of the circuit comprising reactor 22 and valve 2| in the embodiment illustrated in Fig. 1. In the embodiment illustrated in Fig. 3, such component is a component appearing across reactor 22 and is transmitted through a transformer 31 having the primary winding thereof connected across the reactor 22and the secondary winding thereof connected with the load circuit.

Although but two embodiments of the present invention have been illustrated and described, it will be apparent to those skilled in the art that various changes and modifications may be made therein without departing from the spirit oi the 5 invention or from the scope of the appended claims.

It is claimed and desired to secure by Letters Patent:

1. In a system for controlling the iiow oi. electric current, an electric current supply line, electric translation means connected with said line and comprising an alternating current winding and an electric valve having an anode, a control electrode and a cathode; an electric current output line connected with said translation means, a circuit including a source of direct current, an inductive reactor and a capacitor constituting an oscillative element; a resistorconnected across said capacitor, electric valve means controlling the flow of current through said circuit, discharge controlling means connected for cyclically controlling the operation of said valve means, and means connecting said circuit with said control electrode to impress thereon a potential similar to the potential across a reactive portion of said circuit.

2. In a system for controlling the flow of electric current, an electric current supply line, electric translation means connected with said line and comprising an alternating current winding and an electric valve having an anode, a control electrode and a cathode; an electric current output line connected with said translation means, a circuit including a source of direct current, an

inductive reactor and a capacitor in said circuit constituting an oscillative element; a resistor connected across said capacitor, electric valve means controlling the flow of current through said circuit, discharge controlling means for said valve 40 means, energizing means operating in relation with the voltage cycle of said winding and controlling the action of said discharge controlling means, and means connecting said circuit with said control electrode to impress thereon a potential similar to the potential across a reactive portion of said circuit.

3. In a system for generating a periodic potential, a circuit including a source of direct current, an inductive reactor and a capacitor in said circult constituting an oscillative element; a resistor connected across said capacitor, electric valve means controlling the flow of current through said circuit. discharge controlling means for said valve means, a source of alternating current,

means coupling the second said source with said discharge controlling means for controlling the action of the latter, a load circuit, and means connecting the first said circuit with said load circuit to impress thereon a potential similar to the potential across a reactive portion 0! the first said circuit.

4. In a system for generating a periodic potential, a circuit including a source 01' direct current, an inductive reactor and a capacitor in said circuit constituting an oscillative element; a resistor connected across said capacitor, electric valve means controlling the flow of current through said circuit, discharge controlling means Ior said valve means, a source of alternating current,

means coupling the second said source with the said discharge controlling means for controlling the action oi. the latter, means for regulating the action of the said coupling means, a load circuit, and means connecting the first said circuit with said load circuit to impress thereon a potential similar to the potential across a reactive portion 01' the first said circuit.

5. In a system for generating a. periodic potential, a circuit including a source of direct current, an inductive reactor and a capacitor in said circuit constituting an oscillative element; a resistor connected across said capacitor, an electric valve in said circuit having an anode, a control electrode and a cathode; a source of alternating current, means coupling said source of alternating current with said control electrode for impressing thereon potentials of signs and magnitudes operative to cause said valve to become alternately conductive and non-conductive at recurring intervals in relation with the voltage cycle of the second said source, a load circuit, and means connecting the first said circuit with said load citcult to impress thereon a potential similar to the potential across said reactor and said valve.

6. In a system for generating a periodic potential, a circuit including a source of direct current, an inductive reactor and a capacitor in said circuit constituting an oscillative element; a resistor connected across said capacitor, an electric valve in said circuit having an anode, a control electrode and a cathode; a source of alternating current, means coupling said source of alternating current with said control electrode for impressing thereon potentials of signs and magnitudes operative to cause said valve to be alternately conductive and non-conductive at recurring intervals in relation with the voltage cycle of the second said source, a load circuit, andmeans for connecting said load circuit across said valve and said reactor.

7. In a system for generating a periodic potential, a circuit including a source of direct current, an inductive reactor and a capacitor in said circuit constituting an oscillative element; a resistor connected across said capacitor, an electric valve in said circuit having an anode, a control electrode and a cathode; a source of alternating current, means coupling said source of alternating current with said control electrode for impressing thereon potentials of signs and magnitudes operative to cause said valve to be alternately conductive and non-conductive at recurring intervals in relation with the voltage cycle of the second said source, a load circuit, and means connecting the first said circuit with said load circuit for impressing thereon a potential similar to the potential across said reactor.

8. In a system of the character described, the combination with an oscillative circuit comprising a source of current, a capacitor, an inductive reactor, and an electric valve, of means for rendering said valve alternately conductive and nonconductive to thereby recurringlypermit and prevent flow 0! current through said circuit, a load circuit, means coupling the first said circuit with said load circuit to recurringly impress thereon, from the first said circuit, potential impulses commensurate to the potential across a reactive portion of the first said circuit, and means forming a path for discharging said capacitor.

9. In a system 01' the character described, the combination with an oscillative circuit comprising a source of current, a capacitor, an" inductive reactor, and an electric valve, of means comprising an element of said valve and a second source of current for rendering said valve alternately conductive and non-conductive to thereby recurringly permit and prevent flow of current from the first said source through said circuit, a load iii 2,oas,14e

circuit, and means inductively coupling the first said circuit with said load circuit to recurringly impress thereon, from the first said circuit, potential impulses commensurate to the potential across a reactive portion of the first said circuit.

10. In a system of the character described, the combination with an oscillative circuit comprising an electric valve, a source of current, 9. capacitor, an inductive reactor, of means comprising an element of said valve and a source of current for rendering said valve alternately conductive and non-conductive to thereby recurringly permit and prevent the flow of current through said circuit, a load circuit, and means coupling the first said circuit with said load circuit to recurringly impress thereon, from. the first said circuit, potential impulses commensurate to the potential across said capacitor and the first said source of current.

1,1. The combination with an electric current converting device comprising a cathode and an anode constituting spaced electrodes for the continual vflow of current therebetween, of means for controlling said flow of current comprising 'a control electrode constituting an element of said device, and means for continually exciting said control electrode in such sense as to control the moments of recurring initiation of said flow of current, the second said means comprising a source of current, a series circuit including an inductive reactor, a capacitor and an electric valve connected across said source, means for rendering said valve alternately conductive and non-conductive to thereby recurringly permit and prevent flow of current through said circuit, and means coupling said circuit with said control electrode, whereby potential impulses similar to the potential across a reactive portion of said circuit are continually impressed on said control electrode.

12. The combination with an electric current converting device comprising a cathode and an anode constituting spaced electrodes for the continual new of current therebetween, of means for controlling said flow of current comprising a control electrode constituting an' element of said device, and means for continually exciting said control electrode in such sense as to control the moments of recurring'initiation of said flow of current, the second said means comprising a source of current, a series circuit including an inductive reactor, a capacitor, and an electric valve connected across said source, means for rendering said valve alternately conductive and non-conductive to thereby recurringly permit and prevent flow of current through said circuit and means coupling said control electrode with said reactor, whereby potential impulses similar to the potential across said reactor are continually impressed on said control electrode.

' ISADORE K. DORTORT. 

